Coaxial switch



Feb. 13, 1962 J, E, JENNlNGs 3,021,408

COAXIAL SWITCH Filed May 18, 1959 IN V EN TOR. 1/0 E MME TT JENN/NGSh/ls AT TORNE Y 3,021,408 COAXIAL SWITCH Jo Emmett Jennings, San Jose,Calif., assignor, by mesne assignments, to'Jennings Radio ManufacturingvCorporation, San Jose, Calif., a corporation of?k Delaware Filed May18,1959, Ser. No. 813,935 11 Claims. (Cl. 200-144) I Still anotherobject of the invention is the provision i of a vacuum coaxial switchoperable remotely by an external solenoid utilizing any practical A.C.or D.C. voltage. n

n Still another object of the invention is the provision of avacuumcoaxial switch of substantially 5 kw. ca-

pacity and of extremely small size in comparison with conventionalcoaxial switches having comparable power ratings. g

A still further object of the invention is the provision of a vacuumcoaxial switch requiring minimum power to operate, and constructed frommaterials and in a manner requiring little machining and customprocessing so as to maintain manufacturing costs at a minimum.

The invention possesses other objects some of which with the foregoingwill be brought out in the following description of the invention. Ido'not limit myself to the showing made by the said description and thedrawings, since I may adopt variant forms of the invention within thescope of the appended claims.

Referring to the drawings:

FIG. 1 is a vertical half-sectional view, partly in elevation, showingythe switch contact in its normal springclosed position. Thesolenoid-closed position of the switch contact is shown in dash lines.

FIG. 2 is a horizontal sectional view taken in the plane indicated bythe line 2-2 of FIG. 1.

FIG. 3 is a vertical sectional view taken in the plane indicated by theline 3--3 of FIG. l. Y

FIG. 4 is a fragmentary sectional view illustrating a modified contactstructure. f

All of the figures are drawn approximately four actual size.

Broadly considered, the miniature vacuum coaxial switch of my inventioncomprises a vacuumized envelope including an outer metallic conductor orhermetically sealed shell. Arranged within the outer'conductive shelland rigidly supported thereon are a plurality of inner' conductors whichextend hermetically through the envelope wall and provide spaced contactpoints within theenvelope and terminal leads outside the envelope. Theouter metallic shell is preferably cruciform in shape sjo as ltoaccommodate two axially aligned and spaced transversely extendingcontact points perpendicular to and spaced from a third common contactpoint, all of which are insulated from each other and from theconductive outer shell, and each of which is integrally continuous withAan inner conductor. Mounted within the envelope adjacentfthe threecontact points is a mobile contact. The mobile contact is movable fromoutside contact from outsidethe envelope to make or break acircuitthrough a selected pair of inner conductors.

In more rspecific detail, the miniature vacuum coaxial switch of myinvention comprises a vacuumized envelope formed from an elongatedhollow cylindrical metallic shell or tube 2 diametrically aperturedintermediate its yends to accommodate axially aligned cylindricalconductive terminal sleeves 3. Each sleeve is formed with a reduceddiameter portion 4 extending into the shell 2 through an aperture, and arelatively larger integral terminal portion 6 extending from the shelland provided with threads 7 adapted to receive a conventional coaxialconnector (not shown), for connection of the switch in a coaxialtransmission line. Each of the aligned terminal sleeves is hermeticallybrazed to the shell within the aperture so that a mechanically rigid'andelectrically continuous union is formed therebetween. The oppositelyextending terminal sleeves 3 and shell 2 thus form an integral cruciformouter metallic conductor which completely shields the interior of theenvelope from undesirable radiations.

times the envelope to make or break a circuit between a sey contact areprovided to effect movement of the mobile iExtending into one end of thecylindrical shell 2 and rigidly brazed thereto is a third terminalsleeve 8 having an inner end portion 9 of the same diameter as theportion 4 of each terminal sleeve 3. A reduced diameter cylindricalportion 12 integral with the inner end portion 9 and with the outerthreaded terminal portion 13, fits snugly within the open end of theshell where it is rigidly and hermetically brazed.

Coaxially associated with and supported on each terminal sleeve 3 is `aninner conductor 14 extending through the central aperture of an annularinsulator 16 interposed transversely between the inner conductor and theconductive terminal sleeve 3. The insulator 16 is preferably a ceramicannulus having inner and outer peripheries 17 and 18 metallized andhermetically braz'ed to the inner conductorand terminal sleeve,respectively. Each inner ,conductor thus provides an inner end 19constituting sociated with and supported on the third terminal sleeve 8,by an annular ceramic insulator 23 having an outer metallized periphery24 hermetically brazed across the reduced diameter portion 12 of thesleeve, and an inner metallized periphery 26 hermeticallybrazed aboutthe inner conductor 22. The outer yend portion 27 of the conductor 22constitutes a terminal lead extending out of the envelope, while theinner end 28 of the inner conductor extends into the envelope betweenthe inner ends19 of the conductors 14 to provide a fixed contact pointcommon to both contact points 19. As shown in FIG. l, the common contactpoint 28 is shaped to provide flat contacting surfaces 29 on oppositesides thereof, each parallel to the associated end of the contact point19.

From the aboveitwill be apparent that the sleeves 3 and 8,annularinsulators 16 and 23, and inner conductors 14 and 22, cooperateone with the other and collectively with thev shell 2, to hermeticallyclose this end of the envelope. The cooperative combination of theseelements also provides threeseparate switch terminals having inner andouter conductive elements coaxially arranged and integrally connectedmechanically to give rigidity, while effectively electrically insulatingthe inner conductors one kfrom the other and from the outer conductor.The inner conductor 22 constitutes the common input terminal of theswitch, and is related to surrounding structure in both pro-portion andposition to maintain a uniformly low standing-wave-ratio through theswitch.

Means are provided to hermetically seal the end of the shell 2 oppositethe terminal sleeve 8, and to connect and disconnect the common contactpoint 28 with a selected adjacent contact point 19. Closing the lowerend of the shell 2 is a ilexible metallic bellows 31 extending into theshell 2 in a closed inner end 32, and at its outer open end 33 having acylindrical ange 34 lying snugly within the shell adjacent the endthereof and hermetically brazed thereto.

integrally united at its inner end 36 to the closed inner end 32 of thebellows and extending outwardly therefrom is a metallic stem 37.Adjacent its outer end portion 38, the stem is provided wtih an integralbearing 39 bored transversely of the stem to receive a pivot pin 41having opposite end portions 42 journaled in the annular bearingmounting plate 43. Spaced lugs 44 on the bearing mounting plate abutopposite ends of and conne the stem bearing 39 to restrict movementthereof to pivotal movement in a single plane including the axes of theinner conductors i4 and 22. A cylindrical sleeve 4b brazed to theperiphery of the bearing mounting plate serves to confine the pivot pin41, and also extends beyond the mounting plate in a ange 47 snuglyencircling and brazed about the lower end of the shell 2. Pivotalmovement of the outer end 3S of the stem about the pivot pin 4l thusresults in the inner end 36 of the stem, with bellows attached, beingdisplaced from side to side within the envelope.

Movably mounted within the envelope on the inner closed end of thebellows is a U-shaped mobile contact having spaced resilient contactarms 48 integral with a base 49 which is in turn brazed to a metal cap51 similarly brazed on the metallized upper end portion of a dielectricpillar or post 52. A metal cap 53 brazed to the metallized lower end ofthe post and to the closed inner end or. the bellows insures a rigid andpermanent mounting for the U-shaped mobile contact. The dielectric postis preferably high dielectric strength ceramic, and serves toeffectively insulate the mobile contact from the operating mechanism.

In FIG. l, the resilient arms 43 are shown to extend upwardly, one eachextending between the common contact point 2S and the contact point 19on each side thereof. The parts are proportioned so that when one of thearms 4S engages the contact point 19 with which it is associated, theother contact arm 4S engages the common contact point 2S, thuscompleting a circuit therebetween. Movement of the mobile contact in theopposite direction results in the resilient arms being disengaged fromthe position shown and re-engaged between the common contact point 23and the other contact point i9. in either position a portion of themobile contact lies interposed between the engaged contact points andthe disengaged contact po-int.

In the modified mobile contact structure illustrated in FlG. 4, eachresilient arm 4% is provided on its upper end with an integral contactportion 54 adapted to engage and disengage the associated contact point19. integrally interposed between each contact portion 54 and theassociated surface 29 of common contact 28, is a flexible and conductivemetallic bellows 56. This integral interconnection results in thecontact resistance being substantially halved, and the inductance beingmaterially lessened. Additionally, interposition of the bellows makes itpossible to reduce the spacing between each contact portion 54- and theassociated iixed contact point, thus rendering the switch faster acting.Also favorably affected is the standing-wave-ratio through the switch.

Means are provided outside the envelope operatively .connected with thestem 37 to selectively move the mobile contact into and out ofengagement with the fixed contact points. schematically illustrated inFIG. l is a solenoid 57, having its armature 58 connected by links 59 tothe outer end portion 38 of the stem. A recovery spring 6l connectedwith the armature and links, retains the mobile contact normally closedas shown. Energizing the solenoid causes the stem to be pivotedcounterclo-ckwise about the pin 4i, thus tensioning the spring, whichreturns the mobile contact to its initial position when the solenoid isdeenergized.

Evacuation of the rigid, hermetically sealed envelope is effectedthrough tubulation 62 brazed over an aperture 63 in the shell 2. Fromthe manner in which the stem 37 and bellows are cooperatively related itwill be apparent that inward expansion of the bellows due to evacuationof the envelope is prevented by the stem, but due to its inherentflexibility, the inner end of the bellows is capable of being displacedfrom side to side. Because of its length in relation to the amount oflateral displacement, the stress and strain imposed on the bellows arenegligible, thus contributing to a long bellows and switch life.

l claim:

l. A miniature vacuum coaxial switch comprising a vacuumized envelopeincluding the outer metallic conductor of the switch, a plurality ofinner conductors rigidly supported on the envelope and extendingthereinto to constitute spaced contact points within the envelope andterminal leads outside the envelope, a mobile contact within theenvelope movable from outside thereof to engage or disengage selectedcontact points, said mobile contact having portions thereof sopositioned with respect to said contact points on the conductors thatmovement of the mobile contact to engage selected contact pointsshieldingly interposes one of said portions of the mobile contactbetween the engaged contact points and a disengaged contact pointwhereby power leakage to the disengaged Contact point is prevented, andactuator means mounted on the envelope and operatively connected to themobile contact to effect movement thereof to make or break a circuitthrough selected inner conductors.

2. The combination according to claim l, in which said actuator meansincludes means insulating the mobile contact from the outer conductor.

3. The combination according to claim l, in which said actuator meansincludes a stem pivotally mounted on the envelope, a flexible metallicbellows integrally interposed hermetically between the stem and theouter conductor, and means for insulating said movable contact from saidstem and bellows.

4. A miniature vacuum coaxial switch comprising a vacuumized envelopeincluding an outer metallic conductor constituting a hollow cruciformhousing having at least three integral outer terminals, an innerconductor rigidly supported on the envelope and coaxially associatedwith each outer terminal and extending into the envelope to constitutespaced contact points within the envelope and terminal leads outside theenvelope, a mobile contact within the envelope movable fromoutsidethereof to engage or disengage selected contact points, saidmobile contact having portions thereof so positioned with respect tosaid contact points on the conductors that movement of the mobilecontact to engage selected contact points shieldingly interposes one ofsaid portions,Y

interposed between each said inner conductor and theV connected to themobile contact to effect movement there-` of to make or break a circuitthrough selected inner conductors. p f

7. The combination according to claim 6, in which extending into theshell intermediate its ends, a third integral outer terminal vsleeveextending into one end of fthe shell perpendicular to the irst andsecond terminal sleeves, inner conductors coaxially arranged within theouter terminal sleeves and extending ,into'r theV shell to providespaced contact points within the shell and terminal leads outside theshell,pan annular insulator integrally interposedhermetically betweeneach inner conductor and the associated terminal sleeve, amobile'contact within the shell U-shaped to provide spaced resilientcontact arms extending between adjacent contact points electricallyconductive and'llexiblemeans are provided Y for insulating said mobilecontact from said stern andy bellows.

10. The combinationaccording to claim 9, in which said means forinsulating the mobile contact from the stem and bellows comprises aceramic post interposed between the mobile contact and the bellows.

11. A miniature vacuum coaxial switch comprising an elongatedmetallic-vacuumized shell having first and second integral transverselyextending outer terminal sleeves points.

References Cited in the tile of this patent y UNITED ySTATES PATENTSRe.21,087 Y Rankin May 16,1939 1,784,302 Millikan et al. Dec. 9, 19301,804,086 Brodt May 5, 1931 Y 2,128,427 Means Aug. 30, 1938 f 2,235,010Chaffee; Mar. 18, 1941 2,527,475 Bates Oct. 24, 1950 2,794,087 Jenningset al. May 28, 1957 r2,920,168 Jennings r Jan. 5, 1960 FOREIGN PATENTS y115,662 Australia Aug. 4, 1942 n 476,430 Great Britain Dec. 8, 1937209,454k Sweden July 1, 1940 791,123 Great Britain Feb. 26, 1958 264,433Sweden Ian. 16, 1950 715,392 Great Britain Sept. 15, 1954 ymentV thereofto engage and movable to engage or disengage selected contact points tomake or break a rcircuit therebetween, and

actuator means movably mounted on the shell and operatively connectedtothe mobile contact to effect moveor disengage selected contact

